This invention relates to a vend possible judgement device for a vending machine and, more particularly, to a device capable of performing judgement as to whether vending is possible or not by calculating an amount to be paid as change on the basis of an amount of deposited coins or bills and a set vend price and judging whether the change is payable or not on the basis of the amount to be paid as change and coins and bills stored for paying out of change.
A basic condition on which the vend possible judgement (i.e., judgement that an article is vendible) is made is that an amount of money (K) which is equal to or exceeding a set vend price (SPi) has been deposited, i.e., the condition K.gtoreq.SPi has been satisfied. Since, however, it is necessary to prohibit vending if paying out of change is not possible, it has been customary with prior art vending machines to restrict the condition on which the vend possible judgement is made if there is shortage in coins stored for paying out of change. In a case where coins of a large denomination stored for paying out of change are short but those of a small denomination are sufficient, change corresponding to the coin of the large denomination can be paid out in the coins of the small denomination and, accordingly, vending may be permitted in accordance with the above described basic vend possible condition. In a case, however, where coins of the small denomination stored for paying out of change are short, there is likelihood that paying out of change is not possible. For this reason, in such a case vending is generally permitted only if change is not required (i.e., the deposited amount K coincides with the set vend price SPi) and otherwise is prohibited even if the deposited amount K exceeds the set vend price SPi. If, accordingly, there is shortage in coins stored for paying out of change, particularly in coins of a small denomination, chances of vending will be missed with the result that the operation efficiency of the vending machine will be reduced.
For overcoming such problem, it has been conceived that vending may be permitted even in a case where paying out of change is required if storage of coins of a large denomination stored for paying out of change is sufficient and the change can be paid out in the large denomination coins even if coins of a small denomination are short. For this purpose, Japanese Patent Publication No. 41475/1980, for example, discloses an art according to which, in comparing the deposited amount K with the set vend price SPi, an amount of a predetermined large denomination coin (e.g. 50 yen) is previously added to the set vend price SPi, the result of addition is compared with the deposited amount and the vend possible judgement is made when they coincide with each other (K=SPi+50). The coincidence of the sum of the set vend price and the amount of the large denomination coin with the deposited amount means that difference between the deposited amount and the set vend price, i.e., change, can be paid out in the large denomination coin.
For coping with the problem of shortage of coins and bills stored for paying out of change, Japanese Patent Publication No. 39159/1979 discloses another device according to which numbers of deposited coins for respective denominations are stored in a memory and, in case of shortage of change, vending is allowed only if the change can be paid out by using the coins of the same denomination as the one of the deposited coins. In other words, vending is allowed only if the coins which have just been deposited can be used for change of the vending.
In the prior art vend possible judgement methods as represented by the above described examples, the judgement of shortage of coins and bills stored for paying out of change is made on the basis of a maximum value of an amount of change which can be paid out in a single vending (i.e., whether the amount of coins and bills stored for paying out of change is larger or smaller than this maximum value) and, accordingly, the judgement that coins and bills stored for paying out of change are insufficient will be made despite that there is a small amount of coins or bills left for paying out of change resulting in the judgement that vending is impossible. In the former example of the prior art devices, for instance, if the number of coins and bills stored for paying out of change is below a predetermined number with respect to both a large denomination and a small denomination, the judgement of change shortage is made with the result that vending requiring payout of change is prohibited. However, there can be a case where required change can be paid out by the remaining small amount of coins depending upon the amount of deposited coins and in such case it is not desirable to make the judgement that vending is impossible. In the latter example of the prior art devices in which only the numbers of denominations of the deposited coins are considered, the judgement that change cannot be paid out will be made on the basis of the number of the deposited coins despite that there is a small amount of coins or bills left for paying out of change with the result that vending is prohibited. If, for example, there are two 10-yen coins stored for paying out of change, the set vend price is 80 yen and the deposited coin is a 100-yen coin, the judgement of change shortage will be made, for the maximum number of 10-yen change coins in the judgement of shortage of coins stored for paying out of change is normally set to be 9, and the judgement that payout of change is impossible will be made, for the deposited coin in this case is a single 100-yen coin. As a result, vending is not permitted. Further, it is not usual that a part of deposited coins is directly returned as change (because minimum possible coins are usually deposited) and, accordingly, probability of enlarging sales chances by such method is not very high.